Biased taut line mooring system

ABSTRACT

A buoyant surface object that tends to at all times occupy a fixed predetermined position due to the tensioning of at least two pennant lines that extend outwardly therefrom. Each pennant line is connected to a submerged float. The floats are in turn connected to mooring lines that extend downwardly and outwardly therefrom. The lower ends of the mooring lines are secured to anchors. The floats due to their buoyancy tend to move to positions where their mooring lines would be vertically disposed. This tendency to so move is prevented by the pennant lines. The pennant lines as a result of tending to restrain the buoys from moving are tensioned and when no exterior force is exerted on the surface object maintain the surface object in the predetermined position. In the event that an external force moves the surface object from said predetermined position, the tension on at least one of the pennant lines is increased, and the tension on another of the pennant lines decreased, and an unbalanced force system prevails. As soon as the external force ceases to act on the surface object, the floats move to their initial positions to exert balanced forces on the pennant lines, and the surface object returning to said predetermined position.

United States Patent Clement 1 Nov. 21, 1972 (54] BIASED TAUT LINEMOORING [57] ABSTRACT SYSTEM A buoyant surface object that tends to atall times oc- [72] Inventor: John C. Clement, Cypress, Calif. cupy afixed predetermined position due to the ten sioning of at least twopennant lines that extend out- [73] Asslgnee' g Design fi gCorporawardly therefrom. Each pennant line is connected to a ong eacsubmerged float.

[22] Filed" Sept 1970 The floats are in turn connected to mooring linesthat [2!] Appl. No.: 69,954 extend downwardly and outwardly therefrom.The

lower ends of the mooring lines are secured to Related Appllmtlon Damanchors. The floats due to their buoyancy tend to 3 Continuation of No773,333, Nov. 25 move to positions where their mooring lines would be963, abandone vertically disposed. This tendency to so move is preventedby the pennant lines. The pennant lines as a 521 US. Cl. ..114/230, 9/8R result of tending to restrain the F' mving are 51 Int. Cl ..B63b21/00, B63b 21/52 P when t 9" [58] Field of Search ..1 :4/230; 9/8 RSurface Obie maintain surface Obie predetermined position. In the eventthat an external [56] References Cited force moves the surface objectfrom said predetermined position, the tension on at least one of thepen- UNITED STATES PATENTS nant lines is increased, and the tension onanother of the pennant lines decreased, and an unbalanced force g nisystem prevails. As soon as the external force ceases 0 l to act on thesurface object, the floats move to their Langer initial positions toexert balanced forces on the p Primary Examiner-Trygve M. BlixAtr0rney-Fulwider, Patton, Rieber, Lee & Utecht nant lines, and thesurface object returning to said predetermined position.

8 Claims, 7 Drawing Figures P'A'IENTEDnnvzw m2 SHEET 2 BF 2 FIG.4

INVENTOR. Jan/v 6. 61.5mm?

Afro/away BIASED TAUT LINE MOORING SYSTEM This application is acontinuation of application Ser. No. 778,388 filed Nov. 25, 1968 and nowabandoned.

BACKGROUND OF THE INVENTION a predetermined position on or below thesurface of a '0 body of water, even when said object is subjected toforces of variable magnitude such as those generated by currents, waveaction, wind, and the like.

2. Description of the Prior Art In oceanographic work it is frequentlydesirable to maintain a buoyant surface object, such as aninstrumentation buoy, research platform, or the like, at a predeterminedposition upon a body of water. An anchored, buoyant surface object issubjected to variable forces caused by the action of currents, waves,and the wind, that may act both individually and in concert to move theanchored object a substantial distance from its initial predeterminedposition.

In the past, no mooring system has been available for use with a buoyantsurface object to automatically exert restraining forces on the objectthat increases in magnitude proportional to the displaced distance ofthe object from the initial position thereof, which forces at all timestend to return the object to its initial predetermined position. Thisfailure to heretofore provide a buoyant surface object that will notdeviate a substantial distance from a predetermined position whensubjected to forces of variable magnitude has been detrimental to theeffective carrying out of many oceanographic operations.

A major object of the present invention is to supply a biased taut linemooring system for a buoyant surface object of relatively simplemechanical structure that is easy to set, and automatically tends at alltimes to return a buoyant surface object to a predetermined positionwhen it is subjected to drag-generating forces arising from winds,currents, and wave action, and to maintain the buoyant surface object insaid predetermined location.

A further object of the invention is to provide movable submerged floatmeans that are so anchored as to generate a plurality of outwardlydirected forces which are at all times exerted on the buoyant surfaceobject in such a manner as to tend to maintain said object in apredetermined position where said forces are in equilibrium and ofsubstantially the same magnitude.

Another object of the invention is to supply a method of setting abuoyant surface object at a predetermined fixed location where it at alltimes tends to remain due to outwardly directed forces impressed on aplurality of pennant lines extending from said object and connectedthereto.

SUMMARY OF THE INVENTION A mooring system and method of forming the samefor maintaining a surface buoyant object at a predetermined position ona body of water which includes a plurality of equally spaced pennantlines extending outwardly from said body to a plurality of floats, withsaid floats being so movably anchored as to at all times tend to moveoutwardly and away from said object, and with said floats generating aplurality of opposing forces on said cables that are in equilibrium,only when said object is in said predetermined position.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of asurface buoyant object and mooring system therefor, which mooring systemtends at all times to maintain said object at a predetermined positionon a body of water, and with the position of the system, prior to thesetting operation, being illustrated in phantom line;

FIG. 2 is a top plan view of the surface buoyant object and mooringsystem associated therewith, with positioning of the mooring line,floats, and pennant lines prior to the setting operation being indicatedin phantom line;

FIG. 3 is a diagrammatic view illustrating the steps involved in settingone of the anchors and the float associated therewith;

FIG. 4 is a side elevational view of one of the floats;

FIG. 5 is a fragmentary, vertical, cross-sectional view of one of thefloats, taken on the lines 5-5 of FIG. 4;

FIG. 6 is a top plan view of one of the anchors that may be used withthe mooring system; an

FIG. 7 is a side elevational view of the anchor shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The buoyant surface object A tobe anchored at a predetermined position on the surface of a body ofwater B is illustrated in FIGS. 1 and 2 as being a spar buoy. Threepennant lines C extend outwardly and downwardly from the object A, whichlines are in equally spaced relationship. In the illustration of theinvention shown in FIGS. 1 and 2, three pennant lines are provided.

Three floats D-l, D-2 and 0-3 are provided, which are connected tooutwardly disposed ends of the pennant lines C. Mooring lines E dependfrom floats D-l, D-2 and D3, which lines are connected to individualanchors G. The mooring lines E are of such length that the floats D-l,D-2 and D3 are disposed a substantial distance below the surface 10 ofthe body of water H to minimize the effect of wave action thereupon.

The length of pennant lines C is such that the floats D-l, D-2 and D-3are disposed inwardly towards the object A a substantial distancerelative to the anchors G. Due to the buoyancy of each float D-l, D-2and D-3, it tends at all times to move to a position where it is locateddirectly above the anchor G associated therewith. The tendency of floatsD-l, D-2 and D-3 to move to positions above the anchors G, causestensioning of the pennant lines C by outwardly directed forces F-l, F-2and F-3 thereon, as shown in FIG. 2.

The forces F-l, F-2 and F-3 are of substantially the same magnitude whenthe object A is in said predetermined position and in equilibrium.

Should currents, winds, or wave action tend to move object A towards oneof the floats D-l, D-2 or 0-3, the force F-l, F-Z or F-3 on that pennantline C of the float towards which the object moves, is decreased, andthe forces on the other two pennant lines are increased. In such case.forces F-l, F-2 and F-3 are no longer in equilibrium whereby the mooringsystem is in an unstable condition, but with the forces F-l, F-2 and F-3tending to return to a balanced condition in which they are inequilibrium. However, the forces F-l, F-2 and F- 3 can only be inequilibrium when the object A is in the initial predetermined position.Thus, it will be seen that the object A will automatically return to itsinitial predetermined position due to the action of the floats D-l. D-2and D-3, as soon as the current, wind or wave action which caused anexcursion of the object A from its initial position, has abated.

FIGS. 6 and 7 illustrate the structure of one of the anchors G that issuitable for use with the present mooring system. Each anchor G includesan upwardly extending elongate center member I2 provided with threeequally spaced first legs 14 extending radially from the bottom thereof,as well as three second legs 16 which extend from the top of the member.

First and second legs 14 and 16 are in vertical alignment. and uprightsl8 extend therebetween. Each upright 18 projects through the centeropenings of a number of stacked railroad car wheels 20. The upper end ofthe member 12 is provided with an eye 22 to permit the anchor G to belowered to a desired location on the bottom 24 of the body of water B bymeans ofa cable.

The floats D-l, D-2 and D-3 are structurally identical and one of thesefloats is shown in detail in FIGS. 4 and 5. The exterior configurationof floats D-l, D-2 and D- 3 is preferably that of a surface ofrevolution to minimize any tendency of the floats to pivot or rotaterelative to the mooring lines E to which they are connected. The floatD-3 (FIG. 4) includes a rigid cylindrical shell 26 having an opposedconvex top 28 and convex bottom 30. A tube 32. as shown in FIG. 5,extends downwardly through the center interior of float D-3, and is incommunication with an opening (not shown) in the top 28. The lower endof the tube 32 is secured to the interior surface of the bottom 30 bywelding 34, or the like. The bottom 30 and lower portion of the tube 32cooperatively define a cylindrical body shoulder 36. A ring-shapedbearing 35 is secured to the upper surface of shoulder 36.

As an illustration of the setting operation of the mooring systemdescribed herein, it will be assumed that the object A is to be set at apredetermined surface position in a body of water B which is 3,000 feetdeep. The three anchors G are set on the bottom 38 600 to 900 feetoutwardly from the predetermined location of the object A at the apexesof an imaginary equilateral triangle. The anchors G are, of course,equally spaced apart. The floats D-l, D-2, and D3 are set at a depth ofapproximately 60 feet below the surface of the body of water 8, and thenbiased in toward the object A a horizontal distance of 300 to 400 feetfrom the anchor G associated therewith. This biasing of the floats D-l,D-2, and D-3 requires a tension of eight hundred to eleven hundredpounds on each pennant line C, depending on the positive displacement ofthe floats D. The biased floats D-l D-2, and D-3 are at a depth of 80 to100 feet below the surface 10.

The length of each pennant line C should not be less than 300 feetbecause the angle thereof becomes excessive. Also, the pennant lines Cshould not be too long, because of excessive drag imposed thereon bycurrents. A length of between 300 and 500 feet for each pennant line Cis desirable.

The mooring system is preferably set when the body of water B is calm,the wind low, and a minimum current is running. Also, the predeterminedlocation selected for the object A should be such that the slope of thebottom of the body of water 38 is no greater than I in 20 and the bottomshould not be crossed with peaks and chasms where the anchors could beset too high or too low. The setting operation is conveniently carriedout by use of a tugboat 40 (FIG. 3) from which a boom 42 projectsoutwardly and on the upper end of which a sheave 44 is mounted. Thetugboat 40 is provided with a power-driven winch (not shown) from whicha cable 46 extends to pass over the sheave 44 and downwardly therefrom.

A swivel or book 48 is affixed to the free end of cable 46, as shown inFIG. 7, and is capable of engaging one of the eyes 22. The anchors G andthe floats D-l, D-2 and D3 are supported on the deck of the tugboat 40.The anchors G are raised sequentially from the deck by auxiliaryequipment (not shown) and disposed in positions where they may beconnected to the end of a length of cable 46 that extends downwardlyover the sheave 44.

Each cable 46 also passes downwardly through one of the tubes 32associated with one of the floats D-l, D- 2, D-3, which float has beenmoved outwardly from the tugboat 40 to a floating position. A bottomdetector (not shown) is supported about 60 feet below each anchor G, andthe anchor is then lowered by use of a winch (not shown) on the tugboat40 until the bottom detector indicates that the bottom 38 has beenreached. Thereafter, the winch (not shown) is stopped. After cessationof downward movement of cable 46, a cable rotation member 50 and stop 52are mounted on the cable.

A circular flange 54 projects from each cable rotation housing 50 andseats on one of the bearings 35 when one of the cables 46 is loweredrelative to one of the floats D-l, D-2, or D-3. After one of the cables46 has been lowered to the extent that the stop 52 thereon is in contactwith the cable rotation housing 50 as shown in FIG. 5, the cable islowered until the anchor G associated therewith rests on the bottom 38.The cable is then severed by an electric guillotine or other cuttingmeans, with the set float D-l, D-2, or D-3 then being submergedapproximately 60 feet below the surface 10 of the body of water B. Thecable 46 above described and shown in phantom line in FIG. 3 providesthe mooring line B illustrated in FIG. 1.

Prior to being set, a length of pennant lines C are connected to floatsD-1 and D-2, with the free ends of the pennant lines being connected tosmall buoys (not shown). The object A is then placed in a floatingposition between the two floats D-l, D-2 and the positions of thesefloats and the object A are shown in phantom line in FIG. 2. Two halfpennant lines C also extend from object A that are also connected tosmall buoys (not shown). The buoys (not shown) are removed from the halfpennant lines C, and the free ends of these lines are then connected toprovide the two lines (FIG. 2) that are connected to the floats D-1 andD-2. The position of the floats D-1 and D-2, and the object A asinitially set are shown in phantom line in FIG. 1.

At the time the object A is placed in a floating position as illustratedin FIG. 1, a pulley block 56 is removably secured thereto. The pulleyblock 56 is engaged by a cable 58, one end of which is secured to thefloat D-3 shown in phantom line in FIG. 1, and the other end to apower-driven vessel 60. Object A and float D-3 both have pennant linesof half length connected thereto, with the free ends of these halflengths being connected to small buoys (not shown).

The vessel 60 is caused to move away from the floats D] and D-2, and inso doing, the object A is moved from the positions shown in phantom linein FIGS. 1 and 2 to the positions shown in solid line in these figures.The free ends of the half length pennant lines from object A to FloatD-3 are then connected together to provide the pennant line C shown inFIG. 1. The pulley block 56 may thereafter be removed from the object Aand the setting of the mooring system for the object is completed. Dueto the buoyancy of the floats DOl, D-2, and D-3 and the positioning ofthe anchors G associated therewith, these floats at all times tend tomove away from the object A and exert forces F-l, F-2, and F3 on thepennant lines, which forces are in equilibrium only so long as theobject A is in the predetermined position shown in solid line in FIGS. 1and 2.

Although the mooring system above described is preferred, the object Acan be moored in a desired position by the use of but two floats D-1 andD2 and two anchors G that are in axial alignment with the object, asshown in phantom line in FIG. 2. It will, of course, be apparent that amooring system employing more than three floats and three anchors may beused if desired.

The invention has been illustrated as tending to maintain a buoyantobject at a fixed position on a body of water. However, the inventionmay be used for a like purpose with a non-buoyant object, for thepennant lines will not only maintain the non-buoyant object in a fixedposition but will support the non-buoyant object as well.

lclaim:

I A biased taut line mooring system tending to maintain a buoyant objectat a predetermined position on the surface of a body of water subject towind, current or wave action including:

a plurality of anchors disposed radially outwardly of said position andresting upon the bottom of said body of water;

a plurality of mooring lines extending generally upwardly from andradially inwardly of said anchors, said mooring lines terminating belowthe surface of said body of water;

a plurality of buoyant floats connected to the upper extremities of saidmooring lines, all of said floats being submerged radially inwardly ofsaid anchors below the effect of surface wave action and exerting biasestending to vertically orient said mooring lines; and

a plurality of pennant lines extending from said object to said floatsand all rendered taut and maintained in tension by said biases of saidfloats, said tension in said pennant lines automatically varyingaccording to movement of said object out of said predetermined positionand tending to locate said object in said predetermined position whensaid tension in said pennant lines reaches a balanced condition. 2. Amooring system as defined in claim I wherein said anchors aresubstantially equally spaced from one another.

3. A mooring system as defined in claim 1 wherein said anchors aresubstantially equally spaced from one another and from said object.

4. A mooring system as defined in claim 1 wherein said floats aresubmerged sufficiently below said surface that they are generallyunaffected by wave action on said body of water.

5. A mooring system as defined in claim 1 wherein said floats eachincludes:

a central tube extending therethrough;

bearing means mounted in one end of said tube;

a cable rotation housing disposed in said tube upon said bearing means,and one of said mooring lines extending through said housing; an

a stop in said tube in abutment with said housing, said stop beingaffixed to said mooring line, whereby said float is rotatable relativeto said housing, said stop and said mooring line.

6. A mooring system as defined in claim 1 wherein said anchors andfloats are each three in number and disposed at the apices of imaginary,concentric, equilateral triangles in which said predetermined positionis centered.

7. A mooring system as defined in claim 1 wherein said anchors andfloats are each two in number, with said anchors and floats being inalignment, and with said object being located at equal distances fromsaid floats when in said predetermined position.

8. A method of mooring a buoyant surface object to float at apredetermined position on the surface of a body of water by the use of aplurality of anchors, floats, mooring lines, and pennant lines, whichmethod includes the steps of:

setting said anchors on the bottom of said body of water in equallyspaced relationship to said predetermined position and to one another;

connecting said floats to said anchors by said mooring lines to locateall of said floats in positions below said surface of said body of waterand below the effect of surface wave action;

pulling said floats radially inwardly of said anchors and toward saidobject; and

connecting said pennant lines to said floats and to said object, wherebythe buoyancy of said floats renders said pennant lines taut and undercontinuous tension and whereby any movement of said object away fromsaid predetermined position develops a varying bias in each of saidpennant lines automatically tending to locate said object in saidpredetermined position.

1. A biased taut line mooring system tending to maintain a buoyantobject at a predetermined position on the surface of a body of watersubject to wind, current or wave action including: a plurality ofanchors disposed radially outwardly of said position and resting uponthe bottom of said body of water; a plurality of mooring lines extendinggenerally upwardly from and radially inwardly of said anchors, saidmooring lines terminating below the surface of said body of water; aplurality of buoyant floats connected to the upper extremities of saidmooring lines, all of said floats being submerged radially inwardly ofsaid anchors below the effect of surface wave action and exerting biasestending to vertically orient said mooring lines; and a plurality ofpennant lines extending from said object to said floats and all renderedtaut and maintained in tension by said biases of said floats, saidtension in said pennant lines automatically varying according tomovement of said object out of said predetermined position and tendingto locate said object in said predetermined position when said tensionin said pennant lines reaches a balanced condition.
 1. A biased tautline mooring system tending to maintain a buoyant object at apredetermined position on the surface of a body of water subject towind, current or wave action including: a plurality of anchors disposedradially outwardly of said position and resting upon the bottom of saidbody of water; a plurality of mooring lines extending generally upwardlyfrom and radially inwardly of said anchors, said mooring linesterminating below the surface of said body of water; a plurality ofbuoyant floats connected to the upper extremities of said mooring lines,all of said floats being submerged radially inwardly of said anchorsbelow the effect of surface wave action and exerting biases tending tovertically orient said mooring lines; and a plurality of pennant linesextending from said object to said floats and all rendered taut andmaintained in tension by said biases of said floats, said tension insaid pennant lines automatically varying according to movement of saidobject out of said predetermined position and tending to locate saidobject in said predetermined position when said tension in said pennantlines reaches a balanced condition.
 2. A mooring system as defined inclaim 1 wherein said anchors are substantially equally spaced from oneanother.
 3. A mooring system as defined in claim 1 wherein said anchorsare substantially equally spaced from one another and from said object.4. A mooring system as defined in claim 1 wherein said floats aresubmerged sufficiently below said surface that they are generallyunaffected by wave action on said body of water.
 5. A mooring system asdefined in claim 1 wherein said floats each includes: a central tubeextending therethrough; bearing means mounted in one end of said tube; acable rotation housing disposed in said tube upon said bearing means,and one of said mooring lines extending through said housing; an a stopin said tube in abutment with said housing, said stop being affixed tosaid mooring line, whereby said float is rotatable relative to saidhousing, said stop and said mooring line.
 6. A mooring system as definedin claim 1 wherein said anchors and floats are each three in number anddisposed at the apices of imaginary, concentric, equilateral trianglesin which said predetermined position is centered.
 7. A mooring system asdefined in claim 1 wherein said anchors and floats are each two innumber, with said anchors and floats being in alignment, and with saidobject being located at equal distances from said floats when in saidpredetermined position.